Vapour heating and vapour generating units

ABSTRACT

A VAPOR GENERATING AND SUPERHEATING UNIT HAVING ITS COMPONENTS ARRANGED TO SUPPORT IT IN BOTH HORIZONTAL AND VERTICAL POSITION AND INCLUDING A PLURALITY OF HEADERS DISPOSED ADJACENT ONE OF THE SIDEWALLS, SAID SIDEWALL BEING LOWERMOST WHEN THE UNIT IS IN HORIZONTAL POSITION.   D R A W I N G

United States Patent H 1 [111 3,811,415 Lawrence et al. 1 May 21, 1974 [54] VAPOUR HEATING AND VAPOUR 2,305,611 12/1942 Frisch .L 122/240 GENERATING UNITS 2,800,116 7/1957 Raynor et a1.

3,115,123 12/1963 Smith 122/478 [76] Inventors: Arthur Charles Lawrence, 31

Quinton Ave., London, S.W. 20; Milova" Grgich, 10 Woodstock Primary Examiner-Kenneth W. Sprague Ave, London, l both of Attorney, Agent, or Firm-J. Maguire England [22] Filed: Feb. 1, 1972 [21] Appl. No.: 222,471 [57] ABSTRACT [52] US. Cl. 122/478, 122/510 A vapor generating and superheating unit having its [51] Int. Cl. F22g 7/14 components arranged to support it in both horizontal [58] Field of Search 122/235, 240 R, 476, 478, and vertical position and including a plurality of head- 122/510, 480 ers disposed adjacent one of the sidewalls, said sidewall being lowermost when the unit is in horizontal [56] References Cited position.

UNITED STATES PATENTS 3,266,467 8/1966 Winship 122/510 8 Claims, 8 Drawing Figures PATENTEDMAY 2 1 1974 SHEET 1 OF 6 MTENTED 9974 SHEET 2 BF 6 PATENTEDMAY 21 m4 SHEET UF 6 PATENTEBMAYZ] m SHEU 5 [If 6 PATENTEMY 2 1 m4 SHEETGUF 6 FIG.4

VAPOUR HEATING AND VAPOUR GENERATING UNITS BACKGROUND OF THE INVENTION This invention relates to vapor generating and vapor heating units and can be embodied in a unit which conforms to loading requirements enabling the unit to be transported assembled from factory to site and yet offers, in operation, a relatively high evaporation rate.

SUMMARY OF THE INVENTION In accordance with the present invention, there is provided a vapor generating and vapor heating unit of elongate transportable form including a tubular gastight casing of panels of longitudinally finned tubes welded together extending over the length of the unit, closed at one end by an end wall formed with burner apertures, and providing a flue gas outlet at the other end, a furnace chamber adjoining the end wall, and sinuous tube banks extending across the casing intermediate the furnace chamber and the flue gas outlet, the casing and associated pipework being adapted to support the unit both with the unit extending vertically and with the unit extending horizontally.

In accordance with the present invention, there is also provided vapor generating and vapor heating apparatus including a unit providing an elongate rectangular, gas-tight, casing having at one end an end wall formed with burner apertures and at the other end a flue gas outlet and vapor heating tubes contained within the casing, the unit being such that it may be transported horizontally and brought into its vertical aperture condition by rotation about one corner, and the vapor heating tubes being provided by banks of sinuous tubes extending between headers all of which lie at one side of the casing that during transportation is lowermost.

In accordance with the present invention, there is further provided vapor generating and vapor heating apparatus including a unit providing an elongate, rectangular, gastight casing having at one end an end wall formed with burner apertures and at the other end a flue gas outlet, and vapor heating tubes contained within the casing, wherein the walls of the casing are provided by tubes spaced apart with the spaces between adjacent tubes closed by fins, the tubes extend between distributors at the first end of the casing at which the burner apertures are provided and collectors at the other end of the casing, the space within the casing provides a furnace chamber at the first end of the casing and a vapor heating space at the other, a tubular division wall extends upwardly through the furnace chamber from a distributor at the first end of the easing, the division wall is parallel to two opposed walls of the casing, at the upper end of the furnace chamber alternate tubes of the division wall are connected to extensions that extend towards the first of the opposed walls, the other tubes of the division wall are connected to extensions that extend towards its second of the opposed walls, the extensions discharge into one or more collectors at the other end of the casing, and all the distributors are connected in parallel with each other.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 illustrates an axial section through a vapor generating and vapor superheating unit;

FIG. 2 shows a part section of FIG. I on the line Ila Ila and a part section of FIG. 1 on the line Ilb IIb; and I FIG. 3 shows a horizontal section through a corner of the unit illustrated in FIG. 1.

FIG. 4 shows a part sectional view including alternate embodiments of the invention.

FIG. 5 shows a cross-section view along line 55 of FIG. 4.

FIG. 6 shows a cross-section view along line 6-6 of FIG. 4.

DESCRIPTION OF THE PREFERRED EMBODIMENT The unit shown in the drawings includes a casing 1 of substantially square cross-section formed by longitudinally finned tubes 2 welded together along the fins in a gas-tight manner. A steam and water drum 3 is positioned at, and carried by, the upper end of the casing l and supplies four downcomers 4, which are located at the corners of the casing. The tubes I extend upwardly from distributors 5 to collectors 6. The distributors 5 and collectors 6 are welded to the downcomers to form a rigid structure, the distributors 5 opening into the downcomers 4 while the collectors 6 are without fluid connections with the downcomers. The collectors 6 discharge into the drum 3.

A movable lower end wall 10 closing the base of the casing l is formed of refractory material and is penetrated by four symmetrically arranged burner apertures 11. The space within the casing 1 immediately above the wall 10 acts as the furnace chamber 12 while the space 13 above that contains vapor heating tubes, as will be described more fully later.

A tubular division wall 15 extends centrally of the furnace chamber 12 upwardly from a pair of headers 16 supplied from the downcomers 4 below the lower end wall 10 with tangential triangular tube pitching to the upper end of the furnace chamber where alternate tubes of the wall 15 join extensions 16a, 16b respectively, the extensions reaching to opposed, first and second casing walls 2a and 2b to form an upwardly angled tube screen. The extensions 16a connect into acute angled return bends 17 discharging into further extensions 18 extending across the casing in spaced relationship as a further, upwardly inclined, tube screen. The extensions 18 are connected through bifurcations 19 into a row of upright extensions 20 extending adjacent and parallel to the second casing wall 2b.

The extensions 16b connect into acute angled return bends 21 that discharge into upright extensions 22 through bifurcations 23. Extensions 22 lie along side extensions 20, an extension 20 being aligned with an extension 22 transversal of the rows in which they lie. The rows of upright extensions 20 and 22 connect into collectors 24, welded between the collectors 6 at the upper end portion of the casing, and discharge to the steam and water drum 3. v

The vapor heating tubes in the space 13 include a secondary superheater 30 in the form of a sinuous tube bank immediately above the-screen formed by the further extensions 18, a primary superheater 31 in the form of a sinuous tube bank positioned superjacent the secondary superheater 30 and a secondary economizer 32 in the form of a sinuous tube bank positioned intermediate the primary superheater 31 and the steam and water drum 3. A further primary economizer 34 lies in the flue on the downstream side of the drum 3. The return bends of the sinuous tube banks are positioned by lugs (not shown) respectively welded to the first casing wall 2a and to hanger tubes 36 passing between the sinuous tube panels. The hanger tubes 36 extend from supply headers 37 to the inlet header 30a of the secondary superheater 30. Headers 30a, 30b, 31a, 31b and 32a and 32b for the sinuous tube banks 30, 31 and 32 respectively, are all positioned intermediate the row of upright extensions and 22 and the second casing wall 2b. Baffles 39 extend across the gap between the upright extensions and the wall 2b to insure that the gap does not act as a by pass to the space 13. Connections between the tube banks and their respective headers pass between the gaps between the upright extensions 20 and 22. The lower end of the casing is provided with a downward extension to form a wind box enclosure for burners which are directed to fire upwardly through the lower end wall. The burners are disposed symmetrically, two on each side of the division wall 15.

The casing is stressed to withstand loading to both when the unit is in the operative upright position and when the unit is in a horizontally extending position permitting transportation. When the casing is horizontal, the wall 2b at which the headers lie is lowermost and the unit may be moved from its horizontal to its vertical position by being rotated about a horizontal axis. During the rotation, the wall 2b will lie below the header.

Circumferential buckstays 40 provide additional ridity to the casing and are disposed at regular intervals over the length of the casing around the casing. The buckstays 40 are supported from the downcomers 4 at the corners of the casing by links 41 each pivotally connected to the buckstay 40 and to a lug 42 welded to the downcomer 4. The links permit lateral differential thermal expansion between the buckstays 40 and the casing walls. For additional support of the casing during transport, the links 41 are replaced by brackets 43 bolted to the buckstays 40 and the lugs 42.

Except for the flue and the primary economizer 34, the apparatus illustrated is constructed as a unit in the factory with the casing extending horizontally and supported on the second casing wall 2b, the complete unit being fabricated in this position. In order to provide additional rigidity during transportation, diagonal cross bracing may be provided at the end and middle portions of the unit and packing may be inserted between the tubes of the sinuous tube banks.

Transportation may be effected either by supporting the end portions of the boiler upon wheeled trolleys or by slinging the unit from cantilevered brackets carried on wheeled trolleys positioned beyond the ends of the unit where it is necessary to conform to lower maximum height limits. The unit may be slung from a crane by means of panels attached to the casing walls extending parallel to the tube lengths of the sinuous tube banks. The panels are provided with attachments for connection to the spreader bar of a crane to permit a single hoist lift passing through the center of gravity of the unit. To erect the unit from the horizontal position a crane and spreader bar attachment coupled to the plates is utilized to lift the unit on to site either by offsetting the point of suspension or by tethering the base portion of the unit, the unit upon hoisting is rotated about the base portion. Steadying guys and a juryrig areutilized to effect the final rotation of the unit to the upright position.

Once in the upright position the unit is secured at the base with laterally supporting steel work and the twin flue ducts and primary economizer placed in position at the flange at the flue gas outlet adjacent the steam and water drum.

The operating unit is designed to have a relatively high evaporation rate, for example, 400,000 lbs per hour at high pressure and temperature conditions, for example, 2,400 psi and 1005F. Feedwater is supplied to the primary economizer 34 and flows through the secondary economizer 32 to the steam and water drum 3. From the steam and water drum 3 the water flows downwardly through the downcomers 4 positioned at the corner of the casing to the lower headers 5 and 16 and from the lower headers the water flows upwardly, in natural circulation, through the tubes 2 of the casing walls and through the division wall 12 and the extensions connected to them to the collectors 6 and 24 at the upper portion of the casing which, in turn, discharge into the steam and water separators of the steam and water drum 3. Steam from the drum 3 flows in turn downwardly to the primary superheater 31 and up wardly through the secondary superheater 32 to the superheated steam outlet.

In an alternate embodiment of the invention as shown in FIGS. 4 and 5, the evaporative surface of the unit is increased by locating a further division wall 45 across the casing in a direction perpendicular to the division wall 15 and extending from lower headers 5 positioned in the wind box and supplied by the downcomers 4 of the casing walls to an upper collector (not shown) extending across the casing 1 at the upper end portion of the casing. The further division wall 45 is of tangential tube construction in the lower, furnace chamber portion 12, of the casing l and extends through the sinuous tube banks of the secondary and primary superheaters 30 and 31, respectively, and secondary economizer 32'each of which is thereby split vertically into laterally aligned portions. The upper collector (not shown) discharges to steam and water separators of the steam and water drum 3. The division wall 45 may be one of a plurality and the same number of furnaces discharge into each of the cells formed by the division walls. 1

If it is desired further to increase the evaporative surface, one or more laterally extending additional tube screens are formed by bending the tubes of the further division wall 45 out of the plane of the wall to extend sinuously in spaced relationship at an upward inclination across the interior of the casing. The additional tube screen is, or the additional tube screens are, positioned in one or more of the spaces intermediate the further tube screen and the secondary superheater 30 bank.

In another alternate embodiment of the invention as shown in FIGS. 4 and 6, upright extensions 46 which are connected to extensions 18 and pass between instead of toone side of the sinuous tube banks, so that only the row 22 of further extensions lie adjacent the side wall 2b. The upright extensions 46 replace the hangers 36 of the main embodiment.

While in accordance with the provisions of the statutes there is illustrated and described herein a specific embodiment of the invention, those skilled in the art will understand that changes may be made in the form of the invention covered by the claims, and that certain features of the invention may sometimes be used to advantage without a corresponding use of the other features.

What is claimed is:

1. A vapor generating and superheating unit of elongate transportable form comprising two pairs of opposed casing walls formed of panels of longitudinally finned tubes weldably inter-connected and extending over the length of the unit, said casing walls being weldably joined to form a gas-tight setting of rectangular cross-section, said setting having one end closed by an end wall formed with at least one burner port and the other end open for flue gas outflow, a furnace chamber adjoining the end wall, at least one sinuous tube bank extending between opposed casing walls and intermediate the furnace chamber and said other end, the casing walls being adapted to support the unit in both vertical and horizontal position, at least one header located adjacent to the end wall, a group of tubes disposed within the setting and having one end flow-connected to the header, each of said tubes hving a lower segment lying along a common plane and forming a division wall partitioning said furnace chamber, and upper segment forming a spaced tube screen intermediate the furnace chamber and the sinuous tube bank, said screen being formed by tubes being bent out of the plane of the division wall at alternate levels and extending alternately toward a first and a second of the opposed walls of one of said pairs of easing walls, said upper segment including a spaced tube screen disposed intermediate the first named screen and the sinuous tube bank and being formed by return tube bends of the tubes of the first named screen.

2. A vapor generating and superheating unit according to claim 1 including a group of spaced tubes flow connected to the upper segment of the first named group of tubes and being disposed within the setting and extending longitudinally thereof wherein at least some of the second named group of tubes lies intermediate the sinuous bank and the second casing wall.

3. A vaporgenerating and superheating unit according to claim 2 wherein the remaining tubes of the second named group of tubes extend through the sinuous bank and are supportingly connected therewith.

4. A vapor generating and superheatiiig unit according to claim 2 including a plurality of bifurcated sections, each of the tubes of said second named group of tubes being flow connected to a pair of the return tube bends through a corresponding one of the bifurcated sections.

5. A vapor generating and superheating unit according to claim 3 including a plurality of bifurcated sections and wherein each two of said remaining tubes are flow connected to one of the return tube bends through a corresponding one of the bifurcated sections.

6. A vapor generating and superheating unit according to claim 2 including a plurality of headers flow connected to the tube ends of said sinuous bank and positioned inter-mediate the second named group of tubes and the second casing wall, said tube ends extending through the tube spacing between the tubes of said second named group of tubes.

7. A vapor generating and superheating unit according to claim 1 including at least one pair of tubular walls partitioning the furnace chamber in a direction normal to said division wall, each of said pair of walls being disposed on an opposite side of the division wall and extending over the length of the unit. i

8. A vapor generating and superheating unit according to claim 1 including a plurality of headers operatively associated with said sinuous tube bank, the headers being disposed adjacent one of the casing walls, the unit being in a transportable state when its longitudinal axis extends in a horizontal direction with said one wall being lowermost, and in an operable state when said longitudinal axis extends in a vertical direction. 

